The present invention relates to an inflator assembly that can be suitably adapted to a buckle of an inflatable belt device for protecting an occupant of a vehicle, such as an automobile, in the event of a vehicle collision. Such a device is the subject of Japanese Patent Application No. 2001-375950, filed Dec. 10, 2001, and Japanese Patent Application No. 2002-305985, filed Oct. 21, 2002, both of which are hereby incorporated by reference.
A conventional example of a buckle of an inflatable belt device is disclosed in Japanese Unexamined Patent Application Publication No. H 11-334513 (incorporated by reference herein) and is explained below with reference to FIGS. 10(a), 10(b), and 11. FIG. 10(a) is a front view showing a tongue and a buckle of an inflatable belt device according to the conventional example, and FIG. 10(b) is a perspective view of the buckle. FIG. 11 is a structural illustration without an outer shell showing the state where the tongue is latched to the buckle.
The tongue plate 12 is inserted into a tongue insertion slot 14 of the buckle 4. A latch hole 16 of the tongue plate 12 is engaged with a latch pawl of a latching mechanism 18 in the buckle 4, thereby latching the tongue 2 to the buckle 4. The latching is released by pressing a press button 20 provided in the buckle 4 so that the tongue plate 12 is pushed out of the buckle 4 by a spring (not shown).
A numeral 22 designates a tongue sensing switch for sensing when the tongue plate 12 is inserted deeply into the buckle 4 to complete the latching.
A cylindrical piston 24 is disposed beside the tongue insertion slot 14 in the front end surface of the buckle 4 in such a manner as to allow the protrusion of the piston 24 from the buckle 4. The inside of the piston 24 communicates with the inflator 6.
As shown in FIG. 11, a gas passage (duct) 30, which is composed of a pipe, is in communication with gas ports 26, which are formed in a front end portion of the cylindrical inflator 6, via an inflator holder 28. Fixed to the end of the duct 30 is a base portion of a piston holder 32. The piston holder 32 has a substantially cylindrical shape and is arranged coaxially with the duct 30.
The piston 24 has a substantially cylindrical shape and has a front end which is closed with a cover 34. The cover 34 is provided with tear lines (not shown) composed of shallow grooves formed thererin. When a gas pressure from the inflator 6 is applied, the cover 34 is torn along the tear lines to open.
A bracket 35 extends downwardly from the buckle 4. The buckle 4 is mounted to a vehicle body member (not shown) by inserting a bolt through a bolt hole 36 formed in the bracket 35.
When the tongue 2 is latched to the buckle 4, the front end of the piston 24 confronts the gas inlet of the duct 8 of the tongue 2 as shown in FIG. 11. Normally, the piston 24 is held at the rear side of the piston holder 32.
As the vehicle comes into collision from this state, the inflator 6 is actuated, and gas is supplied to the piston 24 through the duct 30. The piston 24 is pushed up by the gas pressure and thus advances to enter through the gas inlet of the duct 8. Then, the cover 34 is torn to open by the gas pressure, and gas flows into the inflatable belt 1 through the duct 8, thus inflating inflatable belt 1.
In this inflatable belt device, the inflator 6, the duct 30, the piston 24, the piston holder 32, and the inflator holder 28 compose an inflator assembly. Hereinafter, the inflator assembly will be described in detail. In the following description the word “front side” means the downstream side of gas flow from the inflator 6, and the word “rear side” means the upstream side of the gas flow.
The inflator 6 has a substantially cylindrical shape and has gas ports 26 formed in the periphery of a front end portion thereof. The inflator holder 28 has a substantially cylindrical shape to be fitted around the outer periphery of the front end portion of the inflator 6 and retains the inflator 6.
The duct (pipe) 30 for introducing gas from the inflator 6 toward the tongue 2 is connected to the inflator holder 28 by screwing a rear end portion of the duct 30 into a duct connecting portion 39, having a substantially cylindrical shape, of the inflator holder 28 or by inserting the rear end portion of the duct 30 into the duct connecting portion 39 and welding the inserted portion to integrate with the duct connecting portion 39. On the other hand, the duct 30 is connected to the piston holder 32 by screwing a front end portion of the duct 30 into a rear end portion of the piston holder 32 or by inserting the front end portion of the duct 30 into the rear end portion of the piston holder 32 and welding the inserted portion to integrate with the piston holder 32.
The inflator holder 28 has a bracket 37. By fixing the bracket 37 to the buckle 4 with a bolt 38, the inflator assembly is secured to the buckle 4.
In the inflator assembly as described above, the entire length of the duct 30 should be long because the duct (pipe) 30 is required to have, at its rear end portion and its front end portion, connection margins to be screwed or inserted into the duct connecting portion 39 and the rear end portion of the piston holder 32. Accordingly, as the inflator 6 is actuated, the front end portion of the duct 30 may rattle due to vibration of the inflator 6 and/or pressure generated when gas spouts from the inflator 6.
The inflator assembly has another disadvantage in that a lot of time and labor are needed for machining the duct (pipe) 30 to form threaded portions to be screwed into the duct connecting portion 39 of the inflator holder 28 and the rear end portion of the piston holder 32 or for welding after the rear end portion and the front end portion of the duct (pipe) 30 are inserted into the duct connecting portion 39 and the rear end portion of the piston holder 32, respectively.
In the aforementioned inflator assembly, since the duct (pipe) 30 is long, the entire length of the inflator assembly extending along the axis of the inflator 6 and the duct 30 is undesirably long. The inflator 6 may project from the rear end of the buckle 4 when the inflator assembly is arranged to extend in the longitudinal direction of the buckle 4. For this, the inflator 6 is arranged to have its longitudinal direction extending across the longitudinal direction of the buckle 4 as shown in FIGS. 10(a), 10 (b), and 11.
When the inflator 6 is arranged to extend across the buckle 4, the inflator 6 protrudes in the width direction of the buckle 4 so as to significantly disturb the pivotal movement of the buckle 4 about the bolt hole 36 formed in a lower end portion of the bracket 35.
Accordingly, one object of the present invention to provide an inflator assembly which can solve these problems and which has a shorter entire length and can be easily manufactured.